JP2007299759A - Production of distinguishable light under the presence of ambient light - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an apparatus and method for producing distinguishable light in the presence of ambient light. <P>SOLUTION: The method and apparatus for producing distinguishable light in the presence of ambient light is disclosed. This method involves admitting light in a first wavelength band through a first admission port into a first optical cavity at least partially defined by a first reflector operably configured to reflect light form the first optical cavity. The method also involves filtering ambient light reflected into the first optical cavity and entering and exiting a first space defined around the first light admission port so that ambient light outside the first wavelength band is attenuated when ambient light enters and exits into and from the first space. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to lighting assemblies, and more particularly to an apparatus and method for generating distinguishable light in the presence of ambient light.

  High intensity light emitting diodes (LEDs) are more frequently used in various applications including, for example, automotive signal lights or tail lights. The LED emits colored light directly without any additional colored filters, thereby allowing automotive designers to signal lights with transparent outer lenses and reflectors that tend to be more aesthetically attractive than conventional designs. Design can be devised. Unfortunately, the use of transparent outer lenses and reflectors in signal lamp designs can result in poor daytime visibility. This is because light from the sun can enter the signal light housing and be reflected with little or no loss. This light mixes with the light from the LED signal light source, and for external observers, this mixed light appears to be less saturated or “faded” and thus less visible. Other drivers may have difficulty seeing the signal lights due to this problem, which can pose a traffic hazard.

  Typical methods for improving daytime visibility of signal lights involve the use of colored external lenses, optical structures on the outer lenses, or the use of matte or structured outer lenses or reflectors. Each of these methods has limited effectiveness and significantly alters the appearance of the signal light in a manner that is resistant to automotive designers.

  In accordance with one aspect of the present invention, a method for generating distinguishable light in the presence of ambient light is provided. The method includes a first light input port through a first light input port in a first light cavity formed at least in part by a first reflector operatively configured to reflect light from the first light cavity. It involves the step of accepting light in one wavelength band. The method also attenuates ambient light entering and exiting the first space formed around the first light input port when ambient light outside the first wavelength band enters and exits the first space. Accompanied by a filtration step.

Accepting the light can involve accepting light from the light emitting diodes in the space.
Filtering can involve passing ambient light reflected into the space through a filter that forms the space.
Filtering can involve passing ambient light reflected into the space through a filter surrounding the space.

Passing the ambient light through the filter may involve passing the ambient light through a filter positioned between the reflector and the light entrance port.
Passing the ambient light through the filter passes the medium to ambient light impinging on the inner surface of the optical filter medium extending around the first light input port, and reflects back through the medium by a reflective coating on the outer surface of the medium. Can involve stages.
Passing the ambient light through the filter may involve passing the ambient light through a filter having a shape that substantially complements the reflector.
Passing the ambient light through the filter may involve passing the ambient light through a filter having a surface that contacts the surface of the reflector.
Passing the ambient light through the filter may involve passing the ambient light through a filter adjacent to the light input port.

The method includes a second light input port through a second light input port into a second light cavity formed at least in part by a second reflector operatively configured to reflect light from the second light cavity. Receiving light of two wavelength bands, and reflecting ambient light reflected into the second optical cavity into and out of the second space formed around the second light input port, outside the second wavelength band. Filtering the ambient light so that it attenuates as it enters and exits the second space.
Accepting ambient light in the first and second wavelength bands may involve accepting light into first and second optical cavities positioned substantially coaxial with each other.

In accordance with another aspect of the present invention, an apparatus for generating distinguishable light in the presence of ambient light is provided. The apparatus includes a first reflector at least partially forming a first optical cavity configured to reflect light from the first optical cavity, and a first wavelength band of light. A first light input port operatively configured to receive into one optical cavity, and ambient light entering and exiting a first space formed around the first light input port in a first wavelength band And a first filter operatively configured to filter to attenuate ambient light outside the first space as it enters and exits the first space.
The apparatus can further include a first light emitting diode in the first light incident port for emitting light in the first wavelength band into the first space.

The first filter can form a first space.
The first filter can surround the first space.
The first filter can be positioned between the reflector and the first light incident port.
The first filter can be positioned adjacent to the first reflector.
The first filter can have a first shape that is substantially complementary to the first reflector.
The first filter can have a first surface that contacts the surface of the first reflector.

The first filter can be positioned adjacent to the first light incident port.
The first filter can include a first optical medium.
The first filter can include a first optical filter medium having a first outer surface extending around the first light input port and facing in a direction generally away from the first light input port.
The first outer surface can have a substantially parabolic shape.
The first reflector is on the first outer surface such that ambient light impinging on the inner surface of the first optical filter medium passes through the medium and then reflects back through the medium by the first reflective coating. Can include a first reflective coating.

The apparatus is positioned coaxially with the first reflector, at least partially forming a second optical cavity, and configured to be operatively configured to reflect light from the second optical cavity. A second light incident port operatively configured to receive light in the second wavelength band into the second optical cavity, and a second space formed around the second light incident port And a second filter operatively configured to filter ambient light entering and exiting the ambient light outside the second wavelength band to attenuate ambient light when entering and exiting the second space. it can.
The apparatus can further include a second light emitting diode in the second light incident port for emitting light in the second wavelength band into the second space.

The second filter can form a second space.
The second filter can surround the second space.
The second filter can be positioned between the second reflector and the second light incident port.
The second filter can be positioned adjacent to the second light incident port.
The second filter can include a second optical medium.
Other aspects and features of the present invention will become apparent to those skilled in the art upon consideration of the following description of specific embodiments of the invention in conjunction with the accompanying drawings.
The drawings illustrate embodiments of the invention.

  Referring to FIG. 1, an illuminating device that generates distinguishable light in the presence of ambient light according to a first embodiment of the present invention is generally indicated at 10. The apparatus 10 includes a first reflector generally indicated at 12 that forms a first optical cavity 14. A first light incident port 16 is disposed in the optical cavity, and receives light in the first wavelength band into the first optical cavity. A first filter 18 is disposed adjacent to the first light incident port 16, and ambient light entering and exiting the first space 20 formed around the first light incident port is transmitted outside the first wavelength band. So that the ambient light attenuates when entering and exiting the first space. Ambient light can be reflected into the first optical cavity 14 by the first reflector 12, for example.

  In the illustrated embodiment, the device 10 is part of an automotive lighting assembly that serves as a rear combination light, such as for a vehicle taillight / stoplight combination. In this embodiment, the apparatus 10 includes a signal light assembly including an integrated plastic mounting assembly generally indicated at 22 having a flat plastic base 24 and a threaded boss for mounting the assembly to a vehicle, One of the threaded bosses is indicated at 26. The assembly 22 also has a truncated parabolic wall 28 having a surface coated with a reflective coating such as an aluminum alloy that serves as the first reflector 12. The parabolic wall 28 extends from the flat base 24 and is substantially symmetric about the axis 27. The flat base 24 has a substantially circular reflective surface 25 such as an aluminum alloy coated with a reflective coating that is similar or the same as that on the parabolic wall 28.

  In this embodiment, the first light incident port 16 includes an elongated opening that cooperates with the first colored light source 31, and the first colored light source 31 is in this embodiment in the first wavelength band. It includes a plurality of colored light emitting diodes that emit colored light. When the assembly is used in a European car, the colored light emitting diode can include an amber LED that emits amber colored light having a wavelength between about 575 nm and 625 nm, and additionally or alternatively from about 600 nm. A red LED that emits light having a wavelength between about 650 nm may be included. Thus, the first wavelength band includes, for example, a band that includes wavelengths of about 575 nm or more where amber and / or red LEDs are used, or at least about 600 nm or more where only red LEDs are used. It can be defined as a band containing.

In the illustrated embodiment, the colored light-emitting diode of the colored light source is arranged substantially linearly at the center of the base 24 and is oriented to emit light in a direction substantially parallel to the axis 27.
In the illustrated embodiment, the first filter 18 is an optical filter medium such as acrylate plastic that forms the first space 20 so that light entering the first space must pass through the optical filter medium. Including a cylindrical wall. The optical filter medium has characteristics that generally allow light having a wavelength within the first wavelength band to pass substantially unattenuated and attenuate light having a wavelength outside the first wavelength band. Have The first filter 18 can be a filter having a filter characteristic as shown at 43 in FIG. 2, in which case the filter passes a longer wavelength (ie, has a higher% transmittance coefficient) and a shorter wavelength. (Ie, having a lower% transmittance coefficient) is attenuated. In order to show that the first filter 18 has a cut-off wavelength shorter than the wavelength of the amber light spectrum 47, the light spectra 47 and 48 of the amber and red LEDs are superimposed on the filter characteristic 43, respectively. It has been.

Although this specification is described as part of a vehicle taillight assembly, in other applications, different colored LEDs can be used and thus have a shorter wavelength than the colored light produced by such LEDs. It will be appreciated that a filter having the property of attenuating light will be employed.
Referring again to FIG. 1, the flat base 24 has protrusions, only two of which are shown at 30 and 32, but protrude from the base 24 substantially parallel to the axis 27. In this embodiment, the protrusions 30 and 32 are positioned coaxially with the first reflector 12 and form a second optical cavity 52 to reflect light from the second optical cavity. It serves to facilitate the installation of a stoplight assembly, generally designated 34 having 36. Stoplight assembly 34 further includes a second light input port 38 configured to be operable to receive light in the second wavelength band into second optical cavity 52. The stop lamp assembly 34 enters and exits the second space 50 formed around the second light input port 38 such that ambient light outside the second wavelength band attenuates when entering and exiting the second space. Further included is a second filter 40 operatively configured to filter ambient light.

The stoplight assembly 34 includes a lower reflective surface 44 and a tip-cut conical reflective surface 46 that are positioned adjacent and spaced apart from the reflective surface 25 when the stoplight assembly 34 is attached to the protrusions 30 and 32. It consists of an integral plastic member having a second base 42 with a lower side 35. The lower reflective surface 44 and the tip-cut conical reflective surface 46 further form the first optical cavity 14. Accordingly, in this embodiment, the first optical cavity 14 is further formed between the reflecting surface 25, the parabolic reflecting surface 29, the lower reflecting surface 44, and the tip-cut conical reflecting surface 46.
The second base 42 has a flat circular reflecting surface 49. The second reflector 36 includes an integral wall 41 that extends away from the second base 42 and has a second parabolic reflecting surface 39. The second parabolic reflecting surface 39 and the flat circular reflecting surface 49 further form a second optical cavity 52.

In this embodiment, the second light input port 38 is an elongated opening in a second base that cooperates with a second colored light source 51 that includes a colored light emitting diode that emits colored light in a second wavelength band. including. The colored light emitting diode can emit red light having a wavelength between about 600 nm and about 650 nm, for example. In this embodiment, the second wavelength band can be defined as a band including a wavelength of at least about 600 nm, for example. Alternatively, the second wavelength band can be the same as the first wavelength band, i.e., 575 nm or more.
The first and second substantially parabolic reflecting surfaces 29 and 39 and the first and second filters 18 and 40 are substantially coaxial with each other. The first and second light sources 31 and 51 are oriented so as to generally guide light in a direction parallel to the axis 27.

  In the illustrated embodiment, the second filter 40 is an optical filter medium such as acrylate plastic that forms the second space 50 so that light entering the second space must pass through the optical filter medium. Including a cylindrical wall. The optical filter medium has characteristics that generally allow light having a wavelength within the second wavelength band to pass substantially unattenuated and attenuate light having a wavelength outside the first wavelength band. Have In general, the second filter 40 surrounds the second light input port 38.

In the working working surface, the light from the first colored light source 31 is entered into the first optical cavity 14 to strike the parabolic reflecting surface 29 of the first reflector 12 through the first filter 18. Reflected by the lower reflecting surface 44, the reflecting surface 25, and the tip-cut cone reflecting surface 46. The parabolic reflecting surface 29 generally guides the first colored light in the axial direction away from the assembly. A pillow-like surface can be formed on the substantially parabolic reflective surface 29 to allow light to be viewed over a wide angle.
The first filter 18 hardly attenuates the amber light or red light generated by the first colored light source 31, and therefore the first colored light passes through the first filter and passes through the first filter 18. The intensity loss is minimal when exiting the optical cavity 14.

  Amber light, such as sunlight, can enter the first optical cavity 14 and impinge on the substantially parabolic reflecting surface 29, where some of the amber light is reflected to the first filter 18. Through the first space 20 between the lower side 35 of the stoplight assembly 34 and the reflecting surface 25. When amber light such as sunlight enters the first space 20, it is reflected by the lower reflecting surface 44, the tip-cut conical reflecting surface 46, and the reflecting surface 25, and is almost emitted through the first filter 18. Guided to another part of the reflective surface 29 of the object surface can exit the first optical cavity 14 in the axial direction. If the amber light is sunlight, it has a complete spectrum of wavelengths, most of which is attenuated by the first filter 18. Thus, when sunlight passes through the first portion of the first filter 18, it is attenuated, then reflected in the first space 20, and then impinges on the other portion of the substantially parabolic reflecting surface 29. Before, it is further attenuated as it passes through another part of the first filter 18. Thus, sunlight entering the first optical cavity 14 passes through two parts of the first filter 18 and is therefore attenuated twice before exiting the first optical cavity 14. During each pass through each portion of the first filter 18, the amber light is attenuated by the first filter and is therefore less visible than without the first filter. The first colored light generated by the first colored light source 31 passes through the first filter 18 only once and is slightly attenuated by the first filter. Therefore, it looks significantly brighter than the amber light reflected from the first optical cavity 14. Thus, the first colored light exiting the first optical cavity 14 is distinguishable from the amber light upon exiting the optical cavity.

  The stop light assembly 34 enters the second parabolic reflecting surface 39 and the amber light guided toward the opposite portion of the second reflecting surface passes through the second filter 40 and has a bounded first light. Upon entering and exiting the second space 50, it works in the same way in that it passes through the second filter 40 and strikes the opposite portion of the second reflective surface where it is guided substantially axially away from the assembly. At the same time, the red light from the second colored light source 51 in the second space 50 impinges on the second reflecting surface 39, where it is directed substantially axially away from the stoplight assembly. There is only one pass through the second filter 40 and there is minimal or no attenuation by the second filter. The colored light directed away from the stoplight assembly 34 can be mixed with the reflected ambient light reflected as described above, but with the passage of the two parts of the second filter 40 and the associated light on each pass. Due to the attenuation, the intensity of the reflected amber light is reduced, thereby generally less visible than the light produced by the second colored light source 51 and reflected by the second reflective surface 39, the second The light generated by the light source is easier to see in the presence of reflected amber light.

  Referring to FIG. 3, an apparatus according to the second embodiment of the present invention is indicated generally at 60. The apparatus includes a first reflector 62, a first light incident port 64, and a first filter 66. In this embodiment, the first reflector 62 is formed of a body having a paraboloid 68 coated with a reflective coating 70 and having a focal point 72. The first light input port 64 is located approximately at the focal point 72 of the paraboloid 68 and can be fitted with one or more LEDs 76 such that the main emission axis is generally away from the reflector 62. A mount 74 is included. In the illustrated embodiment, there is only one LED 76 that emits red light having a wavelength of about 650 nm.

The first filter 66 has a parabolic outer surface 78 that closely fits adjacent to and contacts the paraboloid of the reflector and is complementary to the paraboloid 68 of the reflector 62. Formed with an optical filter medium including a parabolic plastic color lens. A transparent adhesive (not shown) is used to mechanically couple the outer surface 78 of the lens to the paraboloid 68 of the reflector 62 so that the outer surface is generally directed away from the first light incident port. be able to. The lens has an inner surface 80 that is similar in shape and substantially parabolic to the paraboloid 68 of the reflector 62 that faces generally inward toward the optical cavity.
That is, the first optical cavity 82 is formed by the paraboloid 68 of the reflector 62, and the first filter 66 is in the first optical cavity 82, and the first optical cavity 82 is in the first optical port 64 around the first light incident port 64. The space 84 is formed. In this embodiment, the first space 84 is therefore approximately the same size as the first optical cavity 82.

  On-axis light 81 and some off-axis light 83 supplied by the LED 76 and received in the first space 84 pass directly through the first space without colliding with the reflector 62. Exit one optical cavity 82. Off-axis light 85 at an angle to enter the reflector 62 passes through the first filter 66 before impinging on the reflector, and then passes again through the first filter before exiting the first space 84. pass. However, the first filter 66 allows light having a wavelength in the pass band to pass through in a substantially non-attenuated state so that there is almost no loss of light intensity from the first light incident port 64 reflected by the reflector 62. It has a wavelength passband as shown at 86 in FIG.

  Ambient light incident on the reflector 62 from outside the first optical cavity 82 can be reflected by the reflector into the first space 84, but such light enters the optical cavity or causes the optical cavity to When exiting, it should pass through the first filter 66. As ambient light passes through the first filter 66, ambient light components having wavelengths outside the first passband 86 of the first filter are attenuated. Referring again to FIG. 3, as ambient light passes through the first portion 90 of the first filter 66, it strikes the first portion 91 of the reflector 62 and then the second portion 92 of the first filter. After passing through, the first space 84 is entered. When this light passes through the first space 84 in a substantially non-attenuated state until it passes through the third portion 94 of the first filter 66 and collides with the second portion 96 of the reflector 62, the first filter 66. And finally exit the optical cavity 82. The ambient light guided to the optical cavity 82 is thereby filtered multiple times, and most of the ambient light entering the optical cavity is significantly attenuated before exiting the optical cavity and at the same time off-axis light impinging on the reflector 62 Most of the light that enters the optical cavity through the light input port 64, including, results in exiting the optical cavity with little attenuation. Thus, the light generated by the LED 76 does not disappear in the ambient light and is generally distinguishable from the ambient light.

Referring to FIG. 4, generally indicated at 100 is an apparatus according to a third embodiment of the present invention. All of the components of this embodiment are entirely except that a reflective coating 102 on the parabolic outer surface 78 of the first filter 66 is used instead of the reflector (62 in FIG. 3). This is the same as that shown in FIG. The apparatus is the embodiment shown in FIG. 3 except that ambient light impinging on the inner surface 80 of the first optical filter passes through the filter and is then reflected again by the reflective coating on the outer surface 78 of the filter and through the filter. Functions as described above in connection with
The embodiment shown in FIG. 4 is less costly to manufacture than the embodiment shown in FIG. 3 because no separate structure is used for the reflector.
While specific embodiments of the invention have been illustrated and shown, such embodiments are merely illustrative of the invention and are not to be construed as limiting the invention, which is construed according to the claims. is there.

It is a cutaway perspective view of the illuminating device by the 1st Embodiment of this invention. 2 is a graph of% transmittance and wavelength showing filter characteristics of the first and / or second filters shown in FIG. 1. It is sectional drawing of the illuminating device by the 2nd Embodiment of this invention. It is sectional drawing of the illuminating device by the 3rd Embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Illuminating device 12 1st reflector 14 1st optical cavity 16 1st light incident port 18 1st filter 20 1st space

Claims (48)

A method of generating distinguishable light in the presence of ambient light,
A first wavelength through a first light input port into the first optical cavity formed at least in part by a first reflector operatively configured to reflect light from the first optical cavity. Accepting light in the band,
Ambient light entering and exiting the first space formed around the first light incident port is filtered so that ambient light outside the first wavelength band is attenuated when entering and exiting the first space. Stages,
A method comprising the steps of:   The method of claim 1, wherein the step of accepting light comprises the step of accepting light from light emitting diodes in the space.   The method of claim 1, wherein filtering comprises passing ambient light reflected into the space through a filter that forms the space.   The method of claim 1, wherein filtering comprises passing ambient light reflected into the space through a filter surrounding the space.   5. The method of claim 4, wherein passing ambient light through a filter comprises passing ambient light through a filter positioned between the reflector and the light input port.   Passing the ambient light through the filter passes the medium to ambient light impinging on the inner surface of the optical filter medium extending around the first light incident port, and through the medium by a reflective coating on the outer surface of the medium. 6. The method of claim 5, including the step of reflecting it back.   The method of claim 6, wherein passing ambient light through the filter comprises passing the ambient light through a filter having a shape that substantially complements the reflector.   8. The method of claim 7, wherein passing ambient light through the filter comprises passing the ambient light through a filter having a surface that contacts a surface of the reflector.   6. The method of claim 5, wherein passing ambient light through a filter comprises passing the ambient light through a filter adjacent to the light input port. A second wavelength through a second light input port into the second optical cavity formed at least in part by a second reflector operatively configured to reflect light from the second optical cavity. Accepting light in the band,
Ambient light that is reflected into the second optical cavity and enters and exits the second space formed around the second light incident port is used as ambient light outside the second wavelength band. Filtering to attenuate when entering and exiting the space;
The method of claim 1 further comprising:   11. The method of claim 10, wherein accepting light in the first and second wavelength bands comprises accepting light into first and second optical cavities positioned substantially coaxial with each other. Method. A device for generating distinguishable light in the presence of ambient light,
A first reflector at least partially forming a first optical cavity and operatively configured to reflect light from the first optical cavity;
A first light input port operatively configured to receive light in a first wavelength band into the first optical cavity;
Ambient light entering and exiting a first space formed around the first light entrance port is filtered to attenuate ambient light outside the first wavelength band when entering and exiting the first space. A first filter operatively configured to:
The apparatus characterized by including.   13. The method according to claim 12, further comprising a first light emitting diode in the first light incident port for emitting the light in the first wavelength band into the first space. apparatus.   The apparatus of claim 12, wherein the first filter forms the first space.   The apparatus of claim 12, wherein the first filter surrounds the first space.   16. The apparatus of claim 15, wherein the first filter is positioned between the reflector and the first light incident port.   The apparatus of claim 16, wherein the first filter is positioned adjacent to the first reflector.   The apparatus of claim 17, wherein the first filter has a first shape that substantially complements the first reflector.   The apparatus of claim 18, wherein the first filter has a first surface in contact with a surface of the first reflector.   The apparatus of claim 16, wherein the first filter is positioned adjacent to the first light incident port.   The apparatus of claim 12, wherein the first filter comprises a first optical medium.   The first filter includes a first optical filter medium having a first outer surface extending around the first light incident port and facing in a direction generally away from the first light incident port. The apparatus according to claim 12.   23. The apparatus of claim 22, wherein the first outer surface has a substantially parabolic shape.   The first reflector includes a first reflective coating on the first outer surface so that ambient light impinging on the inner surface of the first optical filter medium passes through the medium and then 24. The apparatus of claim 23, wherein the apparatus is reflected back through the medium by the first reflective coating. A second reflector positioned coaxially with the first reflector, at least partially forming a second optical cavity, and operatively configured to reflect light from the second optical cavity When,
A second light input port operatively configured to receive light in a second wavelength band into the second optical cavity;
Ambient light entering and exiting a second space formed around the second light incident port is filtered to attenuate ambient light outside the second wavelength band when entering and exiting the second space. A second filter configured to be operable,
The apparatus of claim 12, further comprising:   26. The method according to claim 25, further comprising a second light emitting diode in the second light incident port for emitting the light in the second wavelength band into the second space. apparatus.   26. The apparatus of claim 25, wherein the second filter forms the second space.   26. The apparatus of claim 25, wherein the second filter surrounds the second space.   29. The apparatus of claim 28, wherein the second filter is positioned between the second reflector and the second light incident port.   30. The apparatus of claim 29, wherein the second filter is positioned adjacent to the second light incident port.   26. The apparatus of claim 25, wherein the second filter includes a second optical medium. A device for generating distinguishable light in the presence of ambient light,
First reflecting means for at least partially forming a first optical cavity to reflect light from the first optical cavity;
First light incident means for receiving light in a first wavelength band into the first optical cavity;
First attenuation means for attenuating ambient light entering and exiting a first space formed around the first light incident means;
The apparatus characterized by including.   The apparatus of claim 32, wherein the means for entering light comprises a first light emitting diode.   34. The apparatus of claim 33, wherein the first attenuating means forms the first space.   35. The apparatus of claim 34, wherein the first attenuating means includes a first filter surrounding the first space.   36. The apparatus of claim 35, wherein the first filter is positioned between the first reflecting means and the light emitting diode.   The first attenuating means includes a first optical filter medium having a first outer surface extending around the first light incident means and facing in a direction generally away from the first light incident means. 37. The device according to claim 36, characterized in that   38. The apparatus of claim 37, wherein the first outer surface has a substantially parabolic shape.   The first reflecting means includes a first reflective coating on the first outer surface so that ambient light impinging on the inner surface of the first optical filter medium passes through the medium and then The apparatus of claim 38, wherein the first reflective coating reflects back through the medium.   37. The apparatus of claim 36, wherein the first filter is positioned adjacent to the first light emitting diode.   36. The apparatus of claim 35, wherein the first filter comprises a first optical medium. A second reflective means configured to at least partially form a second optical cavity and operative to reflect light from the second optical cavity;
Second light incident means for receiving light in a second wavelength band into the second optical cavity;
Second attenuating means for attenuating ambient light entering and exiting a second space formed around the second light incident means;
The apparatus of claim 32, further comprising:   43. The apparatus of claim 42, wherein the second means for entering light comprises a second light emitting diode.   44. The apparatus of claim 43, wherein the second attenuating means forms the second space.   45. The apparatus of claim 44, wherein the second attenuating means includes a second filter surrounding the second space.   46. The apparatus of claim 45, wherein the second filter is positioned between the second reflecting means and the light emitting diode.   47. The apparatus of claim 46, wherein the second filter is positioned adjacent to the second light emitting diode.   The apparatus of claim 45, wherein the second filter comprises a second optical medium.

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